The long-term of objective of this project is to understand interactions between noradrenergic neurotransmission and steroid responsive brain areas and to relate these interaction to regulation of female reproductive behaviors. Specific aims are (a) to stereotaxically implant in specific brain nuclei drugs which are antagonists or agonists of alpha-receptor subtypes that normally respond to norepinephrine. this set of experiments is aimed at localizing alpha noradrenergic receptor subtypes involved in regulation of female reproductive behavior, (b) to determine the effects of pharmacological blockade of alpha-1 and alpha-2 noradrenergic receptor subtypes on concentrations of progestin, estrogen and androgen receptors in microdissected brain nuclei involved in reproduction. The object of these experiments is to develop a model by which altered noradrenergic subtypes is present in cells which contain estrogen and progestin receptors in brain areas known to mediate female reproduction and (d) to determine whether pharmacological manipulation of noradrenergic transmission during the prenatal period of sexual differentiation of the brain results in permanent changes in concentrations of brain steroid receptors and in permanent changes in reproductive capacity. All of these studies utilize the guinea pig. Study of this species has revealed clear-cut effects of noradrenergic transmission on female reproductive behavior and on the various classes of brain steroid receptors. Understanding of interactions of noradrenergic system with steroid- sensitive brain areas is important for developing a clearer picture of brain mechanisms involved in human reproduction and in catecholamine- steroid interactions that may be involved in mood disorders. Possible prenatal effects of noradrenergic system alterations on adult because they may point to disturbances in this neurotransmitter system as an important etiological factor in human reproductive function deficiencies and perhaps in non-reproductive functions and behaviors as well.